PCI standard allows attaching peripheral
devices to
motherboards. PCI standard not only allows the
expansion cards but also the
integrated circuits. These motherboard integrated circuits are known as planer devices in PCI specifications. PCI is not just an expansion slot. It is a standard for a
computer bus
.
PCI Specifications
PCI Specifications defines the bus and slot standards. Specifications define bus physical size, spacing between wires, electrical properties, data transfer rates, and most important the protocols. The specifications are purchasable from PCISIG (Peripheral Component Interconnect Special Interest Group).
PCI Devices
The PCI devices are simple to use, just plug in the slot and add functionality (Plug & Play). Software is burned in the system especially for PCI configuration. This
firmware configures the space for PCI devices and provides required resources. One device can access either six
memory spaces or six I/O Ports. Moreover some devices contain additional ROM that can run open firmware and executable codes or drivers.
PCI Interrupts handling
PCI device contain level triggered interrupts. The firmware is designed to handle each interrupt uniquely. Devices can share the interrupts. But for better performance a unique interrupt is assigned to each device. Moreover interrupt sharing requires a special hardware.
PCI Versions
PCI has gone through a number of versions. The most advanced of all is
PCIe (PCI express). PCI versions are defined according to the bus width and data rates.
PCI 2.2 was one of the early versions. It provides 533 MB per seconds of data transfer rates. Later PCI – X increased data rates up to 1066 MB/second PCI – X 2.0 provided more improvement and supported 2133MB/s.
Mini PCI
Mini PCI is version of PCI designed especially for small foot print computers such as
Laptops.
Compact PCI is industrial computer standard based on 3U or 6U Euro- card.
Card Bus
It is
PCMCIA standard and advancement over PCI for 32-bit with 33 MHz data rates.
PCI / 104 further advances to PCI / 104 Plus. This is the standard for embedded industrial applications. It has the size of floppy disk and limited number of input and out put connections. It is suitable for applications with limited space in requirement specifications. Being extremely integrated the problem is the power consumption, cooling and limited number of inputs and outputs.
